Dr. Ruth Westheimer’s joie de vivre is infectious when she answers the phone from her Washington Heights apartment in New York City, where she has resided for 50 years.

“Hi there! How are you?”

Her signature chirp is girlish yet firm, and still rich with the accent of her native Frankfurt, Germany. At 85, the pioneering sex therapist, talk show host and author is a force to be reckoned with.

And she still delights in talking about sex.

In her upcoming book, “The Scrooge Defect,” Westheimer argues that “anybody (of means) who can’t give to good causes can’t be a good lover. Because a good lover has to be generous and has to rejoice in the pleasure of the partner. So it’s going to be a fun book.”

And, she adds, “It’s going to have some funny illustrations in it.”

On the celebrated and criticized themes of such books as “Fifty Shades of Grey,” Westheimer notes the importance of erotic reading for the human sexual psyche, especially women:

“It’s not great literature, but I’ve read all three volumes because it proves my point that women do get aroused by sexually explicit material … it’s not true that only men get aroused.”

But for the faint of heart she cheerfully offers this advice: “There might be some parts that you just might not want to read — so turn the page.”

An advocate for “sexual literacy,” Westheimer celebrates how far we’ve come in talking frankly about sex, noting that media has “changed … the vocabulary.” But, she says, we still have a long way to go.

When it comes to her opinion of what the most pressing issues of modern relationships are, she doesn’t hesitate:

“I think the most pressing problem is still the question of communicating, and of loneliness. Plenty of people are lonely … that is true for homosexuals and for heterosexuals.”

Westheimer herself faced tragic loneliness early on. In 1939, at age 10, she was sent to a Swiss orphanage for Jewish children escaping the Holocaust; she would later learn her parents had died, likely at Auschwitz. Yet even as a child suffering the ravages of war and loss, Westheimer — then Karola Ruth Siegel — connected with people intimately, and maintains those connections today.

“I was an only child when I left Frankfurt,” she said. “But in the orphanage we became like brothers and sisters. (Jan. 5) was 75 years from the day that I left Germany — Jan. 5, 1939. And I have friends — we talk to each other — who also left on that same children’s transport. One is in Switzerland, one is in Israel, one is in Canada. We are good friends. It helped us survive the war and the terrible feeling of becoming an orphan.”

Her extraordinary life was dramatized in the play, “Becoming Dr. Ruth,” starring Debra Jo Rupp (best known for her role as the mother on “That ’70s Show”).

The play, which just closed off-Broadway last month, chronicled the seemingly impossible rise of the Holocaust orphan: From her time training as a sniper in Israel with freedom fighters to her work as a kindergarten teacher in Paris and eventually her emigration to New York City, where her work on a large-scale study of women’s reproductive health at Planned Parenthood of NYC piqued her interest in human sexuality.

Her meteoric rise as a radio and television host — which made her an international star — also was depicted.

Asked what it was like to see Rupp “become Dr. Ruth” on stage, she proclaimed Rupp “a wonderful actress.” Westheimer saw the show many times, and gleefully reported, “I had to pinch myself and say, ‘That’s not you on stage. That’s Debra Jo Rupp. Not Dr. Ruth.’ ”

She adds, “(Rupp) is a little taller than me. Everybody’s a little taller than me.”

In keeping with her diminutive stature — Westheimer is 4 feet 7 inches tall — she is an avid collector of miniature dolls, figurines and artifacts, including museum-quality dollhouses and erotically-themed items from around the world. She said they helped her regain feelings of control after her loss of control as a child.

Westheimer particularly loves the turtle figurines, seemingly drawing a parallel between the living creature and herself. The animal must “stick its neck out, otherwise it doesn’t move,” she said.

The turtle’s progress isn’t the only thing that interests her.

“I am going to the Galapagos. I have to see how turtles make love,” she said. “And this summer I’m going to South Africa to see how the big animals — tigers, lions — how they make babies. My area of research is human sexuality, not animal sexuality — I’m not a veterinarian. But I want to see what they do, anyway.”

She’ll continue to educate during her upcoming visit to Des Moines.

“I will talk about sexual matters, because that’s what they like me to talk about. I will talk about sexual literacy. I will talk about where we are now and what else we have to work on.”

Yet Westheimer continues to treat her audience with kindness, and respect our reticence.

“I’m going to take questions, and they never have to say ‘I.’ They can say ‘A friend of mine has a question.’ ”

She adds sweetly, ever happy being Dr. Ruth, “I’m going to have a very nice time there.”